From: Jeff Law <jeffreyalaw@gmail.com>
To: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] PR tree-optimization/109417 - Check if dependency is valid before using in may_recompute_p.
Date: Wed, 5 Apr 2023 15:52:36 -0600 [thread overview]
Message-ID: <428a4619-9653-ff0b-8092-25efc933ba80@gmail.com> (raw)
In-Reply-To: <a1a81da3-99ab-482e-14aa-59a8f1025ffe@redhat.com>
On 4/5/23 14:10, Andrew MacLeod via Gcc-patches wrote:
> When a statement is first processed, any SSA_NAMEs that are dependencies
> are cached for quick future access.
>
> if we ;later rewrite the statement (say propagate a constant into it),
> its possible the ssa-name in this cache is no longer active. Normally
> this is not a problem, but the changed to may_recompute_p forgot to take
> that into account, and was checking a dependency from the cache that was
> in the SSA_NAME_FREE_LIST. It thus had no SSA_NAME_DEF_STMT when we were
> expecting one.
>
> This patch simply rejects dependencies from consideration if they are in
> the free list.
>
> Bootstrapping on x86_64-pc-linux-gnu and presuming no regressio0ns, OK
> for trunk?
eek. So you've got a released name in the cache? What happens if the
name gets released, then re-used? Aren't you going to get bogus results
in that case?
jeff
next prev parent reply other threads:[~2023-04-05 21:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-05 20:10 Andrew MacLeod
2023-04-05 21:52 ` Jeff Law [this message]
2023-04-11 9:21 ` Richard Biener
2023-04-24 13:51 ` Andrew MacLeod
2023-04-25 7:17 ` Richard Biener
2023-04-26 2:34 ` Jeff Law
2023-04-26 19:26 ` [COMMITTED 1/5] PR tree-optimization/109417 - Don't save ssa-name pointer in dependency cache Andrew MacLeod
2023-04-06 10:38 ` [PATCH] PR tree-optimization/109417 - Check if dependency is valid before using in may_recompute_p Jakub Jelinek
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